We plan to determine the optimum conditions for ascites cell mRNA stimulation of an in vitro protein synthesizing system from ascites cells; this system should be dependent upon ribosomes, tRNA, and proteins factors as well as mRNA. We hope to identify the site of mengovirus-induced inhibition of protein synthesis in ascites cells. This will be approached by isolating ribosomes, tRNA, and protein factors from mengovirus-infected ascites cells and substituting these individually in the above in vitro protein synthesizing system. Both viral RNA and ascites cell mRNA will be used as message in these experiments, and inhibition of protein synthesis by double stranded viral RNA will be investigated in both cases. Also, components of the protein synthesizing zystem will be isolated from interferon-treated ascites cells and checked for their ability to substitute in the ascites mRNA system but not in the viral RNA system. Work will continue on the characterization of the poly(A)-containing RNAs from the cytoplasm and nucleus of ascites cells. The nature of the 5'-terminal nucleotides will be investigated as well as the effect of virus infection on the length of the poly(A) regions in these mocleules. Also, the ability of poly(A)-containing nuclear RNA to stimulate the in vitro protein synthesizing system will be studied.